Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$196.85	11.614%	$219.7122	$219.71	$219.70	$219.70
Purchase #2	$62.27	5.444%	$65.66	$65.66	$65.65	$65.70
Purchase #3	$79.62	4.800%	$83.4418	$83.44	$83.45	$83.40
Purchase #4	$52.45	12.566%	$59.0409	$59.04	$59.05	$59.00
Purchase #5	$159.60	8.680%	$173.4533	$173.45	$173.45	$173.50
Purchase #6	$199.50	6.699%	$212.8645	$212.86	$212.85	$212.90
Purchase #7	$16.59	13.129%	$18.7681	$18.77	$18.75	$18.80
7 purchase totals =	$766.88		$832.9408	$832.93	$832.90	$833.00